The present invention relates to a method and sewing unit for folding a strip of cloth which is subsequently to be sewn onto a blank, both workpieces having previously been laid out, prior to the folding, at a layout position near a sewing machine, and then transported to the sewing machine. It relates further to a sewing unit for carrying out the method.
A device for combining a pocket trim strip and a pocket bag to make a trouser pocket is disclosed in European Unexamined Patent No. OS 0 238 980. This and all other prior art materials cited herein are incorporated by reference.
With this device, a folded cloth edge of the pocket trim can be sewn by means of a sewing machine onto the pocket bag consisting of lining fabric. The known device consists essentially of a frame with a work table, a sewing machine arranged approximately centrally thereon, a sewing-material conveyor arranged, as seen in the direction of transport of the material to be sewn, in advance of and immediately adjacent the sewing point, and a folding device alongside the sewing machine conveyor but further removed from the sewing point.
A pocket bag blank is laid out suitably for sewing in accordance with corresponding markings at a layout point, which is the designation for the area of the work table which is in the immediate vicinity of the folding device. A folding-plate of the folding device is then lowered onto the pocket bag blank and clamps it firmly to the work table. A pocket-trim blank with the front side facing downward is now placed in accordance with corresponding markings on the folding-plate, protruding with its longitudinal sides beyond the folding-plate on both sides.
A hold-down plate of the folding device is thereupon lowered onto the upper, protruding region of the pocket trim blank and thus clamps it firmly to the pocket bag blank, the hold-down plate--as seen from the position of the operator--being located behind the folding-plate. The folding-plate is now lifted slightly and then displaced horizontally toward the rear, i.e. away from the operator, whereby the strip of pocket trim, which is now pressed onto the pocket bag only by the hold-down plate, is folded around the front edge of the hold-down plate by the folding-plate which is being displaced rearward. The folded part of the pocket-trim strip now lies with the front side up and is held in clamped position between the folding-plate and the hold-down plate.
The sewing-material conveyor is thereupon displaced opposite the direction of transport of the material to be sewn, so that it is located above but upstream from the folding device. Thereupon the sewing material clip forming part of the sewing material conveyor is lowered onto the folded pocket-trim strip and the hold-down plate below it, which is now pulled out rearward by horizontal movement. Thus only the sewing material clip still presses against the folded pocket-trim strip and the pocket bag and subsequently conveys both to the sewing point of the sewing machine.
From the description just given, a substantial disadvantage of the known device can be noted, which resides in the fact that the layout point is occupied for too long a period of time, during both the folding process which also takes place there and further the process of being taken up by the sewing-material conveyor. The layout point can be utilized only relatively late in the entire work cycle for laying out the next two parts which are to be subsequently sewn. Thus, it is not possible to simultaneously sew two sewing parts, while laying out two further parts which are to be sewn next. Thus, the total cycle time is excessive. Furthermore, the known device has the disadvantage inherent in the method that the unfolded edge of the pocket-trim strip cannot be aligned congruently with the corresponding edge of the pocket bag when both parts are laid out.
Also known, from printed publication SpP 2358-a-0279--Ti-1 of Kochs Adler AG, which has been available to the public, is an automatic machine for sewing on pockets--shown as the sewn-on pockets on shirts, blouses or jackets or the sewn-on back pockets on trousers--in which the blank of a pocket to be sewn on is laid out suitably for sewing at a layout point on an upper plate and the main part of the material to be sewn is laid out suitably for sewing on a further lower plate. By a temporary movement of both separately arranged plates, both parts to be sewn are simultaneously brought to a transfer point, the main part of the material to be sewn being placed directly on the work table and the pocket blank being introduced into a folding device located above the transfer place which is in its open position. The pocket blank is folded on three sides and then lowered onto the main part of the material to be sewn. The sewing process then commences. This known automatic machine for sewing on pockets does not make it possible to bring the main part of the material to be sewn, together with the pocket blank, from the layout place to the transfer place while in a stacked arrangement.